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2 years ago

How much heat, in joules, is required to warm a metal disc from 19 °C to 33 °C? The

Chemistry

1 answer:

zalisa [80]2 years ago

3 0

Answer:

Q = 96.6 j

Explanation:

Given data:

Heat required = ?

Initial temperature = 19°C

Final temperature = 33°C

Mass of disc = 3.0 g

Specific heat capacity = 2.3 J/g.°C

Solution:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 33°C - 19°C

ΔT = 14°C

Q = 3.0 g×2.3 J/g.°C × 14°C

Q = 96.6 j

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A buffer solution is composed of 4.00 4.00 mol of acid and 3.25 3.25 mol of the conjugate base. If the p K a pKa of the acid is

Reika [66]

Answer: The pH of the buffer is 4.61

Explanation:

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[\text{conjuagate base}]}{[\text{acid}]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of weak acid = 4.70

$[\text{conjuagate base}]}$ = moles of conjugate base = 3.25 moles

$[\text{acid}]$ = Moles of acid = 4.00 moles

pH = ?

Putting values in above equation, we get:

$pH=4.70+\log(\frac{3.25}{4.00})\\\\pH=4.61$

Hence, the pH of the buffer is 4.61

8 0

3 years ago

Calculate the concentration of hydronium and hydroxide ions in a 0.050 M solution of nitric acid.

Mazyrski [523]

Answer:

[H₃O⁺] = 0.05 M & [OH⁻] = 2.0 x 10⁻¹³.

Explanation:

HNO₃ is completely ionized in water as:

HNO₃ + H₂O → H₃O⁺ + NO₃⁻.

The concentration of hydronium ion is equal to the concentration of HNO₃:

[H₃O⁺] = 0.05 M.

∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.

∴ [OH⁻] = 10⁻¹⁴/[H₃O⁺] = 10⁻¹⁴/0.05 = 2.0 x 10⁻¹³.

3 0

2 years ago

What mass of copper is deposited when a current of 10.0a is passed through a solution of copper(ii) nitrate for 30.6 seconds?

asambeis [7]

Data Given:

Time = t = 30.6 s

Current = I = 10 A

Faradays Constant = F = 96500

Chemical equivalent = e = 63.54/2 = 31.77 g

Amount Deposited = W = ?

Solution:
According to Faraday's Law,

W = I t e / F

Putting Values,

W = (10 A × 30.6 s × 31.77 g) ÷ 96500

W = 0.100 g

Result:
0.100 g of Cu²⁺ is deposited.

3 0

3 years ago

Ca(s) + O₂(g) + S(s) → CaSO4(s)

san4es73 [151]

The mass of Calcium required to complete this reaction is 4.008 g.

Law of conservation of mass states that In a closed system, mass cannot be produced or destroyed, but it can be changed from one form to another.
The mass of the chemical constituents before a chemical reaction is equal to the mass of the constituents after the reaction.
In several disciplines, including chemistry, mechanics, and fluid dynamics, the idea of mass conservation is widely applied.

In the given reaction mass of product after completion of reaction is 13.614 g that means total mass of constituents before reaction should also be 13.614.

So,

mass of Ca + mass of O₂ + mass of S = mass of CaSO4

Ca + 6.400 g + 3.206 g = 13.614 g

mass of Ca = 13.614 - 9.606 = 4.008 g

Therefore, by law of conservation of mass 4.008 g of Ca is required for the completion of the reaction.

Learn more about mass conservation here:

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5 0

1 year ago

Help me with this science question on the middle one..

viktelen [127]

Networks of feeding relationships is correct

8 0

2 years ago